Radio apparatus



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RADIO APPARATUS.

APPLICATION FILED IUNE 13. 1922.

Patented Dec. 5, 1922.

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RADIO APPARATUS.

APPLICATION F|LED1uNE13.1922.

1 ,437,772. Patented Dec. 5, 1922.

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vide means on a receiver apparatus may be protected against heavy surges and electrostatic 'also be protected when not in use by direct apuntaba. s, 1922.

UNITED STA-TES /JoH'N B. NowLAN, or DENVER, MENTS, or Two-'muws PATENT fOFFICE.

DENVER, COLORADO.

RADIO APPARATUS.

Appiication med June 1a, 1922.

whereby signals transmitted on adjacentwavelengths may be received and isolated for reproduction without undue interference.

Another object of my invention is to provide a circuit arrangement in a radio receiving apparatus for securing extreme` accuracy in the coupling of the tuned circuits of the receiving apparatus.

VA further object of the inventionis to provide a construction of coupler forsecuring accurate adjustment of coupling of the tuned circuits of the receiving apparatus.

A still further object of my invention is to provide circuit connections and an arrangement of parts whereby simplicity in adjustment, compactness and selectivity in the different parts of the receiver circuits is secured. v

Another object of the invention is to propanel whereby the charges, and may connection of the antenna with ground.

Other and further objects of my invention will be understood aS the specification progresses by reference to the accompanying drawings in which Figure l is a front plan view of the radio receiving apparatus; Fig. 2 is a lan view of the coupling coilsl employed 1n my receiver; Fig. 3 is a horizontal sectional Viewv taken througlithe coupling coils of my receiver; Fig. 4 is a sectional view of the coupling coils taken on line 4-4 of Fig. 3;.and Fig. 5 shows the circuit arrangement of my receiving apparatus.

.the rear thereof and housed `winding are Serial N0. 568,023.

It will be understood thatthe principles of my invention may be embodied in various forms and that detalls are not material. The present embodiment of the invention, therefore, is to be considered as merely indicative. The form illustrated in the drawings and hereinafter described in detail has been found to be one of the practical embodiments and capable of efficient operation and practical in construction.

The radio receiving apparatus of the present invention comprises an insulated panel carrying the radio equipment supported lon within a cabinetzl The apparatus includes a radiofrequency oscillating circuit which may be an antenna ground circuit or a' coil'collector circuit or.a ground s stein balanced against a free 'ended extended conductor. The oscillation circuit shown in the drawings. includes a primary inductance tapped at sei lected points to switch contacts whereby the desired amount of inductance may be included in the oscillating-circuit.

Inductively associated' with the primary two coupling-coils, arranged at opposite ends of the primary inductance and adjustably mounted with relation to the primary inductance. One of lthe coupling coils forms the secondary and carries an inductance tapped at selected intervals and arranged with a mechanical switch and position-varying means whereby the period and coupling of the circuit associated with the coupling coil may be varied. p By means of. this secondary coupling coil I secure broad adjustment of coupling between the circuits. I' provide a Vernier adjustment coil series connected with the broad adjustment coil whereby accurate adjustment in coupling between the circuit including the primary inductance and the secondary receiving circuit is secured. Thev vernier coil is constructed of small inductance relatively to the inductance of the broad adjustment coil.4 The .coupled Vcircuit including the broad adjustment coifl and the Vernier adjustment is provided witl tuning means and connectedY to ,an electron tube detector circuit. A selective bypass condenser is connected in the output circuit of the detector tube in shunt with the primary winding of anlaudio frequency transformer, the secondary of whiclhconnects to the input circuit of a multistage audio frequency electron tube amplifier. All of the tubes have their lament circuits and plate circuits supplied from common A and B batteries. On the receiver panel of the apparatus I provide connections for loading the primary inductance, the broad adjustment secondary coupling coil and the Vernier coupling coil.

The grid condenser employed in the grid circuit of the electron tube detector is of the\ variable type and a switch is provided on the receiver for selectively cutting out the grid leak or connecting the grid leak in shunt with the grid condenser. The panel is also provided with connections and a switch for securing different values of plate potential for the electron tubes. On theface of the panel I provide a safety gap across the terminals connect-ing to the radiofrequency oscillating circuit with plug means for bridging the gap and shunting the circuit to ground when the apparatus is not in use.

Referrin now more particularly to the drawings, igure 1 represents in plan viewthe arrangement of parts in the receiver. Reference character 1 designates the panel which may be of bakelite or other insulating material. Terminals 2 and 4 for connection to an antenna ground system or other radiofrequency collecting circuit are mounted on the face of the panel. The split tubular members 5 and 6 are mounted on the panel and electrically connected respectively with terminals 2 and 4 forming a safely gap for discharge of heavy surges from antenna to ground without destruction to the receiver.

Carried within clip 7 on the face of panel 1` is a plug 8 which may be removed from the clip and inserted between `,the split tubular members 5 and 6 shunting the antenna and ground circuit when the receiving apparatus is not in use. Mounted on the rear of the panel is primary inductance coil support 9 containing an inductance winding 1() as indicated in Fi s. 2 and 3. The inductance is provided wlth taps 11 which are electrically connected to switch contact points 12 mounted on the side of the panel adjacent the inductance coil 10. The coil support 9 is secured to the rear of panel 1 by members 14 and 16. Switch arm 17 is arranged to move over the switch contacts 12 under control of switch knob 18 operated from the front of the panel. The switch shaft 19 carries indicator 20 moving over scale 21 which may be graduated in terms of wavelength to be received or symbolically desi ating the position of the indicator for'tbx reception of concerts from broadcast stations located in different parts of the country.

Couplin coil support 22 is arranged adjacent tie primary coil and pivotally mounted with relation thereto. The coil support 22 carries secondary winding 24 from which taps 25 are taken at different intervals to switch Contact points 26 carried by insulated disk 33. Disk 33 is suitably mounted within the coil support 22 by members 33a. Flexible leads are taken from this disk to the other parts of the receiving apparatus. The position of coil support 22 may be changed relative to coil support 9 by rotative movement of knob 27 with its associated indicator 23 (Fig. l) operating over dial 38 and secured to sleeve 28 which is in turn permanently secured by means of ianges and machine screws 29 to the coil support 22. "A shaft 30 is arranged concentrically Within the sleeve 28 passing loosely through sleeve bearing 35 in one side of coil support 22 and pivotally secured at 32 in support 34. The shaft 30 carries switch arm 31 operative over switch contacts 26 by rotation of insulated knob 36. The shaft 30 carries indicator 37 which operates over dial 38.

At the opposite end of the rimary coil support 9 I mount the Vernier coupling 'coil 40. This coil carries a winding 41of much smaller inductance than the secondinductance 24, and is mechanically rotatable by shaft 42 pivotally mounted in coil support 9 at 45 and 46 and operated from the front of the panel b knob 44. Flexible leads are taken from t e coil to the other parts of the receiving circuit. The shaft carries an indicator 47 operative over scale 48 on the face of the panel. The receiver includes electron tube detector 50 and electron tubes 51 and 52 connected in a multi- Stage amplifier circuit as shown in Fig. 5. Condenser 54 is arranged for tuning the secondary and Vernier circuit. This condenser is mounted upon the rear of panel land is operated 'by means of knob 55 carrying indicator 56 operative over dial 57. Grid leak 59 and grid condenser 58 are connected into the electron tube detector circuit. The condenser 58 is operat ed from the front of the panel by knob 61 carrying indicator 62 operating over dial 63. A switch 64 is provided on the receiver panel for either connecting the grid leak 59 across the grid condenser 58 or disconnecting the grid leak 59 from the circuit. In the output circuit of the electron tube detector 50, an audio frequency iron core transformer 65 is connected. Shunted across the primary windin 65a of the transformer 65 I provide a ra iofrequency by-pass condenser 66 variable by taps by means of switch 67 indicated upon the panel as having pointer 68 moving over dial 69. The secondary winding 65b of the audio frequency transformer 65 connects to the input circuit of electron tube amplifier 51. A second audio frequency transformer 70 is connected in the output circuit of electron tube amplifier 51. In the output circuit of the last electron tube amplifier 52 I connect a responsive device 72 here represented as a pair of telephone receivers. Any type of loud speaker reproducer may be employed in the output circuit of the'last electron tube amplifier.

The filament circuits of all of the electron tubes are supplied from a common A battery and the filament temperature controlled by rheostat 73. The plate circuits of the electron tubes are supplied from a common B battery. A switch 74 may be provided on the panel for choosing the best operating plate potential. For this purpose binding posts 75 are provided to which leads from different-potentials of the B battery may be connected. Terminals 76 are provided for A battery connection and completion of the plate circuit. Telephone jack 78 is provided for quick connection of telephone receivers 72 or other form of reproducer. Binding posts 79 are provided for loading the primary circuit. inding posts 80 are provided for loading the vernier coil, while binding posts 81 are provided `for the insertion of inductance in the secondary circuit.

In the operation of my radio receiver the plug 8 is removed from the split tubular members 5 and 6 with terminals 2 and 4 connected to an antenna ground system. The filaments of the electron tubes are brought up to an' electron emitting temperature by controlling rheostat 73. Knob 18 is rotated tocut into the antenna and ground circuit the required amount of inductance for reception of a desiredwav'e length. Knob 36 is then rotated to bring the secondary circuit into approximate resonance with the antenna ground circuit. Adjus'tment is made of the variable condensers by rotation of knobs 55 and 61. Thelcoupling ofthe secondary coil is then selected by rotation of knob 27. Fine selectivity of coupling is then obtained by choosmg the position of coil 40 by` operating knob/44 until a high degree of selectivity in coupling of thesecondary oscillating circuit with relation to the primary oscillating circuit is secured. The construction of vernier coil having a smaller amount ofinductance than the secondary coil permits such an (accurate degree of coupling-to be secured that I have isolated and received signals transmitted si- `multaneo1`sly on wave lengths on bands closely approximating each other. i Y WhileI have described the invention in a particular embodiment, it is understood that I intend no limitations beyond the scope ofk ary circuit beginning at one' end .of said pair of windings and continuing in a single direction through said other secondary' winding to the end thereof, said ends forming the sole terminals of said secondary circuit for connection to radio receiving apparatus.

2. In a radio receiving apparatus the combination 'of a primary winding and a secondary circuit comprising a pair of windings each directly connected in series and each cumulatively coupled to said primary winding, and means for adjusting the .coupling of each of said windings independently of the other.

3.y In a radio receiving apparatus the combination'of a primary circuit including an adjustable inductance and a secondary circuit including asecondary winding, means for tuning said secondary -circuit to resonance with said primary circuit, coupling means for .broadly varying the coupling between said primary and secondary circuit, and additional means directly connected in series .with said coupling meansl and cumulatively coupled with said' primary circuit for securing fine adjustment in coupling between said circuits. i

4. In a radio receiving .apparatus the `combination of a primary circuit including anv adjustable inductance anda secondary circuit including a secondary winding, means for tuning said'isecondary circuit to resonance with said primary circuit,- coupling means mounted ad'acent said inductance for broadly. varyingqt e coupling between said primary and secondary circuit, and additional means mounted adjacent said indue.-

tance and directly connected in series with said coupling means` but oppositel Y tioned relatively thereto and cumu atively coupled with `said primary circuit for securing fine adjustment in coupling between said circuits. l

5. In a radio vreceiving apparatus a primary oscillating circuitincluding a primary inductance, a'divided secondary oscillating circuit comprising a pair of inductances each directly connected in series and each cumulatively coupled with said primary inductance, said pair of inductances bein rotatably mounted, each at opposite ends o 'said primary inductance, one .of said pair of inductances having means for broadly adjusting the coupling between said'primary oscillatconnected in series and each cumulatively coupled with said primary winding, one of said coils having a greater physical length than the other of saidl coils, and means for independently rotating said coils with respect to said primary Winding.

ln testimony whereof I aix my signature.

JOHN B. NOWLAN. 

